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| Geochemistry, U-Pb Geochronology and Sr-Nd-Hf Isotopes of the Early Cretaceous Volcanic Rocks in the Northern Da Hinggan Mountains | |
| 作者姓名： | HU Xinlu YAO Shuzhen HE Mouchun DING Zhenju CHEN Bin |
| 作者单位： | 1 Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China 2 Key Laboratory of Tectonics and Petroleum Resources, Ministry of Education, Wuhan 430074, China 3 State Key Laboratory of Geological Process and Mineral Resources, China University of Geosciences,Wuhan 430074, China |
| 基金项目： | This research was supported by the resource compensation of Heilongjiang Province (Grant Nos. SDK2010-25) and the Special Scientific Research Fund of Public Welfare Profession of China (Grant Nos. 201211008). |
| 摘 要： | Whole-rock geochemical, zircon U-Pb geochronological and Sr-Nd-Hf isotopic data are presented for the Early Cretaceous volcanic rocks from the northern Da Hinggan Mountains. The volcanic rocks generally display high SiO2(73.19–77.68 wt%) and Na2O+K2O(6.53–8.98 wt%) contents, with enrichment in Rb, Th, U, Pb and LREE, and depletion in Nb, Ta, P and Ti. Three rhyolite samples, one rhyolite porphyry sample, and one volcanic breccia sample yield weighted mean 206Pb/238 U ages of 135.1±1.2 Ma, 116.5±1.1 Ma, 121.9±1.0 Ma, 118.1±0.9 Ma and 116.9±1.4 Ma, respectively. All these rocks have moderate(87Sr/86Sr)i values of 0.704912 to 0.705896, slightly negative εNd(t) values of –1.4 to –0.1, and positive εHf(t) values of 3.7 to 8. Their zircon Hf and whole-rock Nd isotopic model ages range from 594 to 1024 Ma. These results suggest that the Early Cretaceous volcanic rocks were originated from melting of subducted oceanic crust and associated sediments during the closure of the Mongol-Okhotsk Ocean. |
| 关 键 词： | U-Pb geochronology Sr-Nd-Hf isotopes volcanic rocks Early Cretaceous Da Hinggan Mountains |
| 收稿时间： | 1/3/2014 12:00:00 AM |
| 修稿时间： | 6/8/2014 12:00:00 AM |
Geochemistry, U-Pb Geochronology and Sr-Nd-Hf Isotopes of the Early Cretaceous Volcanic Rocks in the Northern Da Hinggan Mountains |
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| Authors: | HU Xinlu YAO Shuzhen HE Mouchun DING Zhenju and CHEN Bin |
| Institution: | 1. Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China 2. Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China;Key Laboratory of Tectonics and Petroleum Resources, Ministry of Education, Wuhan 430074, China 3. Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China;State Key Laboratory of Geological Process and Mineral Resources, China University of Geosciences,Wuhan 430074, China |
| Abstract: | Whole‐rock geochemical, zircon U‐Pb geochronological and Sr‐Nd‐Hf isotopic data are presented for the Early Cretaceous volcanic rocks from the northern Da Hinggan Mountains. The volcanic rocks generally display high SiO2 (73.19–77.68 wt%) and Na2O+K2O (6.53–8.98 wt%) contents, with enrichment in Rb, Th, U, Pb and LREE, and depletion in Nb, Ta, P and Ti. Three rhyolite samples, one rhyolite porphyry sample, and one volcanic breccia sample yield weighted mean 206pb/238U ages of 135.1±1.2 Ma, 116.5±1.1 Ma, 121.9±1.0 Ma, 118.1±0.9 Ma and 116.9±1.4 Ma, respectively. All these rocks have moderate (87Sr/86Sr)i values of 0.704912 to 0.705896, slightly negative εNd(t) values of –1.4 to –0.1, and positive εHf(t) values of 3.7 to 8. Their zircon Hf and whole‐rock Nd isotopic model ages range from 594 to 1024 Ma. These results suggest that the Early Cretaceous volcanic rocks were originated from melting of subducted oceanic crust and associated sediments during the closure of the Mongol‐Okhotsk Ocean. |
| Keywords: | U-Pb geochronology Sr-Nd-Hf isotopes volcanic rocks Early Cretaceous Da Hinggan Mountains |
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